John Battelle appears to have scooped Google by releasing a draft of Google's Open Social press release. Google Operating System gives a pretty good rundown of what it's all about so I won't rehash that here. What I do think is interesting is the defacto social network that Google's just created.
The launch partners (Orkut, Hi5, Ning, Friendster, LinkedIn, ...) are an impressive collection of social networks that aren't Facebook or MySpace, but the biggest launch partner hasn't been listed.
Google already has a massive social graph, it's all your contacts in GMail and friends in GoogleTalk. Google already uses this social graph to show you a news feed created by your 'friends' in Shared Stuff. Google have said that the GMail contact manager is going to be migrated into Google's other services, and your Shared Stuff profile has already been re-used in Google Maps.
Now we have Open Social, and it doesn't take too much imagination to see iGoogle supporting Open Social widgets. Suddenly you can create an iGoogle tab that displays Shared Stuff feeds and Facebook style social apps that use your GMail contacts as friends. Want to know more about a friend? Just view their 'social profile', and with Open Social you've got a world of 3rd party developers ready to go.
Without having to release a 'new' social network Google already have. Friends, profiles, social apps, picture albums, news feeds, IM, inbox messaging -- just by adding a social layer on top of their existing properties, Google has scooped Facebook.